THE future of two long-running tribunals at Dublin Castle is being privately questioned in political circles for the first time amid fears they could continue into 2012 and leave the taxpayer with a final bill of almost €1bn.

While the main political parties remain reluctant to publicly criticise the Mahon and Moriarty tribunals, senior government and opposition deputies have told the Sunday Tribune that the prospect of calling time on the tribunals "is being discussed tentatively by serious people in politics". The growing unease in political circles at the likely cost to the exchequer from the tribunals is likely to be heightened by the revelation today that James Gogarty was awarded costs of €3.56m by a tribunal.

A recent Supreme Court judgement – which stated that the Flood tribunal had "concealed without justification" allegations made by Gogarty relevant to his credibility has prompted a "sea change" in how the tribunals are perceived in Leinster House, senior political figures said.

The judgement followed an admission by the Moriarty tribunal that it had made errors, something which has also concentrated minds in political circles.

Sources stressed that although there were no impending moves by the Oireachtas to end the tribunals, matters were likely to "reach a tipping point".

Fine Gael leader Enda Kenny will this week table a number of Dáil questions on Moriarty, including asking the Taoiseach the projected additional costs of the tribunal's decision to hold additional public sittings. Labour leader Eamon Gilmore has also put down a more routine question asking about the Moriarty tribunal's likely final cost.

A motion is also due before the Fianna Fáil parliamentary party, put down by Senator Jim Walsh, calling for the legal fees paid to tribunal lawyers to be more than halved, as proposed – but never implemented – by the government in 2004.

Bernard Allen, the chairman of the Dáil's Public Accounts Committee – which monitors state spending – has also signalled he will be calling figures from the Taoiseach's department to examine if the costs of Moriarty have been effectively controlled.

In a further sign of the changed climate, the Sunday Tribune has also learned that legal advisers to Fine Gael have been in correspondence with the Moriarty tribunal challenging the tribunal's interpretation that a cheque for $50,000 given to Fine Gael by Telenor – a shareholder in Esat Digifone – falls within its terms of reference.

Some political sources believe that Moriarty could now run until 2012. They predict a series of further challenges to the tribunal's preliminary findings, first issued over 18 months ago. The recent stunning development whereby the Danish consultant who advised the Department of Communications on the running of the mobile phone licence competition in 1995 is now willing to give evidence means the tribunal is highly unlikely to issue a final report this year. Michael Andersen's evidence is likely to be highly critical of the tribunal's modus operandi, further increasing the pressure on Moriarty.

A Supreme Court challenge to the Mahon tribunal by businessmen Owen O'Callaghan could also add to the duration of that tribunal. O'Callaghan is arguing that before any final report is published, all affected parties should be issued with preliminary findings, as has happened with Moriarty. This greatly increases the chances of findings being picked apart before the final report and has caused considerable delays at Moriarty.

Latest figures show that the bill to date for Moriarty is €40m – the majority of which is made up of fees paid to tribunal lawyers – while the Mahon Tribunal has cost €90m (half of which has gone to tribunal lawyers). Moriarty is currently costing an estimated €1m-plus a month, and third party costs – the legal fees of witnesses or those who assisted the tribunal in other ways – are likely to add considerably to its final bill. For example, the combined legal fees of Denis O'Brien, Michael Lowry, the Department of Communications and Dermot Desmond are likely to add a further €40m to that bill and some tribunal watchers are predicting the total cost will be in excess of €250m.

The bill for Mahon is likely to be a multiple of that, particularly following the Sup­reme Court ruling that the tribunal had no power to deny costs to witnesses on the basis of claiming they had "obstructed and hindered" the tribunal. This verdict leaves it open to the many witnesses so criticised in earlier reports to seek their costs. The tribunal has already paid out nearly €10m in third party costs including €3.5m to Gogarty, €295,000 to PJ Mara, €1m to RTE and €482,768 to Fianna Fail. Some legal figures believe the final bill of the two tribunals could run to €1bn as predicted three years ago by then Tanaiste Michael McDowell.